Decoration device and game machine

ABSTRACT

A decoration device has a display panel having a cylindrical surface shape with curvature in a first direction on which a first pattern is provided, a light source to emit visible light, and a light guide plate with a diffusing surface opposes the display panel, the diffusing surface having a concave cylindrical surface shape, an exit surface opposing the diffusing surface having a convex cylindrical surface shape. The light guide plate is provided such that the first pattern is visible from the exit surface side. The light guide plate has a plurality of prisms that are formed in the diffusing surface and reflect the visible light that enters the light guide plate from the light source through an incident surface toward the exit surface. An angle between a reflecting surface of each prism and the diffusing surface increases as the distance of the prism from the incident surface increases.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2015-129210 filed Jun. 26, 2015, the entire contents of which areincorporated herein by reference.

FIELD

The present invention relates to a decoration device having a lightguide plate and a game machine having such a decoration device.

BACKGROUND

Conventionally, there are game machines such as slot machines or pinballmachines that are provided with a decoration device that shows a patternsuch as a logo mark or characters depicted on a display panel to gamersby spreading the light from a light source over a wide range with alight guide plate and using that light to illuminate the display panelon which the pattern is depicted (e.g., see JP 2011-244930).

With the decoration device disclosed in JP 2011-244930, switching thepattern that is displayed was not envisaged. On the other hand, beingable to switch the pattern that is displayed according to the state ofthe game is preferable in order to enhance the gamer's enjoyment.Meanwhile, an illumination device that has a tabularly formed lightguide plate having light transmittance and that causes a pattern thatdepends on the incident direction of light on the light guide plate tobe displayed has been proposed (e.g., see JP 2003-519810).

For example, the illumination device disclosed in JP 2003-519810 has apanel made from a light transmissive material, and the panel has a lightexit window, a back wall opposing the light exit window, and lighttransmissive first and second end surfaces that are arranged between thelight exit window and the back wall in different positions to eachother. A first optical symbol formed on the back wall is displayed as aresult of light that enters the panel from a light source opposing thefirst end surface being reflected by a plurality of triangular prismsarranged side-by-side on the first optical symbol and exiting from alight exit surface. On the other hand, a second optical symbol formed onthe back wall is displayed as a result of light that enters the panelfrom a light source opposing the second end surface being reflected by aplurality of triangular prisms arranged side-by-side on the secondoptical symbol and exiting from the light exit surface.

JP 2011-244930 and JP 2003-519810 are examples of background art.

SUMMARY

In the illumination device disclosed in JP 2003-519810, a light sourceis provided for every pattern to be displayed. Thus, in the case wherethis illumination device is installed in a game machine, an arrangementspace for every light source needs to be secured in the game machine.Since the wiring and number of substrates for driving these lightsources also increase when the number of light sources increases, thisconfiguration leads to an increase in cost and is not preferable.Furthermore, securing space for wiring paths becomes difficult as thenumber of light sources increases, resulting in the internal structureof a game machine becoming more complex.

Also, it is envisaged that the light guide plate disclosed in JP2011-244930 and the illumination device disclosed JP 2003-519810 will beprovided in a tabular region. On the other hand, slot machines have astructure with a curved surface such as a drum, and in the case ofcarrying out presentation of such a structure, the light guide platedisclosed in JP 2011-244930 and the illumination device disclosed in JP2003-519810 cannot be directly utilized.

In view of this, an object of the present invention is to provide adecoration device that is providable in a structure with a curvedsurface, and is able to suppress the number of the light sourcesrequired in switching display patterns.

A decoration device is provided as one mode of the present invention.This decoration device has a display panel formed to have a cylindricalsurface shape with curvature in a first direction, and on which a firstpattern is provided, a light source configured to emit visible light,and a light guide plate arranged such that a diffusing surface thatdiffuses visible light incident thereon after being emitted from thelight source opposes the display panel, the diffusing surface beingformed to have a concave cylindrical surface shape with curvature in thefirst direction, an exit surface opposing the diffusing surface beingformed to have a convex cylindrical surface shape with curvature in thefirst direction, and the light guide plate being constituted such thatthe first pattern is visible from the exit surface side. The light guideplate has an incident surface formed on an end surface that opposes thelight source in the first direction of the light guide plate, and aplurality of prisms that are formed in the diffusing surface and reflectvisible light that enters the light guide plate from the incidentsurface toward the exit surface. Each of the plurality of prisms has areflecting surface oriented toward the incident surface side, and anangle between the reflecting surface and the diffusing surface increasesas a distance of the prism from the incident surface increases.

In this decoration device, preferably the plurality of prisms arearranged along a second pattern.

Furthermore, in this decoration device, preferably each of the pluralityof prisms is formed such that an area of the reflecting surfaceincreases, the closer the prism is to the incident surface among theplurality of prisms.

A game machine is provided as another mode of the present invention.This game machine has any of the above decoration devices.

A decoration device according to the present invention achieves theeffects of being providable in a structure with a curved surface, andbeing able to suppress the number of the light sources required toswitch display patterns.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram of a slot machine providedwith a drum unit having light guide plates and decoration devicesaccording to one embodiment of the present invention.

FIG. 2 is a schematic perspective view of an entire drum unit accordingto one embodiment of the present invention.

FIG. 3A is a schematic perspective view of an individual drum that isincluded in the drum unit, and FIG. 3B is an exploded perspective viewof the drum.

FIG. 4A is an enlarged partial view of a light guide plate that isincluded in the drum, and FIG. 4B is a cross-sectional side view of thelight guide plate as seen from the direction of arrows AA′ in FIG. 4A.

FIG. 5A is a schematic perspective view of a decoration device accordingto one embodiment of the present invention, and FIG. 5B is an explodedperspective view of the decoration device.

FIG. 6A is an enlarged partial view of a light guide plate that isincluded in the decoration device, and FIG. 6B is a schematic partialcross-sectional view of the light guide plate in vertical cross-section.

DETAILED DESCRIPTION

Hereinafter, a decoration device according to one embodiment of thepresent invention will be described, with reference to the drawings.This decoration device has a light guide plate in which a diffusingsurface that diffuses incident light has a shape curved into a concavecylindrical surface, so as to be arrangeable, in a drum unit including aplurality of cylindrically formed drums, along the surface of each drumnear the boundary of the drum. An exit surface opposing the diffusingsurface of the light guide plate also has a shape curved into a convexcylindrical surface. Furthermore, both ends of the light guide plate inthe direction in which the light guide plate has curvature are eachformed as an incident surface opposing a light source. A plurality ofprisms that reflect visible light that has been emitted from the lightsource and entered the light guide plate toward the exit surface areformed in the diffusing surface. The plurality of prisms arerespectively arrayed according to the shape of the pattern to bedisplayed. Each prism is formed such that the angle of a reflectingsurface to the diffusing surface increases, the more distant the prismis from the incident surface, so that light propagated inside the lightguide plate exits toward the gamer.

Furthermore, a cylindrically formed display panel having a differentpattern of a surface thereof is provided on the diffusing surface sideof this light guide plate, and even when the light source is off, thegamer can see that pattern through the light guide plate.

Note that, hereinafter, for convenience of description, the sideopposing the gamer is deemed to be the front surface, and the oppositeside is deemed to be the back surface.

FIG. 1 is a schematic configuration diagram of a slot machine providedwith a drum unit having light guide plates and decoration devicesaccording to one embodiment of the present invention. As shown in FIG.1, a slot machine 100 has a main body casing 1, which is the main bodyof the game machine, a drum unit 2, a start lever 3, and stop buttons 4a to 4 c.

Also, the slot machine 100 has, inside the main body casing 1, a controlcircuit (not shown) that controls the components of the slot machine100, a power supply circuit (not shown) that supplies power to thecomponents of the slot machine 100, and a token storage and dischargemechanism (not shown) for temporarily storing tokens and for dischargingtokens according to a control signal from the control circuit.

An opening 11 is formed in an upper middle portion of the front surfaceof the main body casing 1, and a portion of the drum unit 2 is visiblethrough the opening 11. Also, a token insertion slot 13 for insertingtokens is formed in the upper surface of a frame 12 on the lower side ofthe opening 11.

The drum unit 2 has three drums 21-1 to 21-3. The drums 21-1 to 21-3 areeach separately rotatable according to a control signal from the controlcircuit, with a rotation shaft (not shown) that is substantiallyhorizontal and substantially parallel to the front surface of the mainbody casing 1 as the rotation center. The surfaces of the drums 21-1 to21-3 are each divided in the rotation direction into a plurality ofregions having substantially the same width, and various patterns aredepicted in the different regions, with a portion of these regions beingvisible to the gamer through the opening 11. Note that the drum unit 2will be discussed in detail later.

The start lever 3 is provided on the left side when facing the frontsurface of the frame 12 of the main body casing 1. Also, the stopbuttons 4 a to 4 c are provided substantially in the middle of the frontsurface of the frame 12. The stop buttons 4 a to 4 c respectivelycorrespond to the drums 21-1 to 21-3.

A token discharge port 14 for discharging tokens is formed in a lowerportion of the front surface of the main body casing 1. A token receiver15 for preventing discharged tokens from dropping to the ground isattached below the token discharge port 14.

When the start lever 3 is operated after a token is inserted into thetoken insertion slot 13, a signal indicating that the start lever 3 wasoperated is transmitted to the control circuit. The control circuit thenstarts rotation of the drums 21 to 23.

Thereafter, when any of the stop buttons 4 a to 4 c providedsubstantially in the middle of the front surface of the frame 12 of themain body casing 1 is pressed, the control circuit receives a signalfrom the button that was pressed indicating that the button was pressed,and stops rotation of the drum corresponding to the button that waspressed. Alternatively, any of the drums 21-1 to 21-3 whosecorresponding stop button is not pressed before a predetermined periodelapses after starting the rotation is stopped by the control circuitafter the predetermined period has elapsed. When the same pattern isaligned in a row across all of the drums at the point in time at whichall the drums have stopped, the control circuit discharges apredetermined number of tokens that depends on the pattern through thetoken discharge port 14.

Next, the drum unit 2 will be described in detail.

FIG. 2 is a schematic perspective view of the entire drum unit 2. Asshown in FIG. 2, the drum unit 2 has the three drums 21-1 to 21-3, andfour decoration devices 22-1 to 22-4. As discussed above, the drums 21-1to 21-3 are each separately rotatable according to a control signal fromthe control circuit, with a rotation shaft (not shown) that issubstantially horizontal and substantially parallel to the front surfaceof the main body casing 1 as the rotation center. Also, the decorationdevices 22-1 to 22-4 are respectively arranged near the boundaries ofthe drums 21-1 to 21-3, such that the longitudinal direction thereof isin the rotation direction of the drums 21-1 to 21-3, that is, in thevertical direction. The decoration devices 22-1 to 22-4 are capable ofswitching between and displaying a plurality of patterns according to acontrol signal from the control circuit. Note that each of thedecoration devices 22-1 to 22-4 has a light guide plate according to oneembodiment of the present invention.

Note that because the drums 21-1 to 21-3 have the same structure, thedrum 21-1 will be described hereinafter. Similarly, because thedecoration devices 22-1 to 22-4 have the same structure except for thepatterns that are displayed, the decoration device 22-1 will bedescribed hereinafter.

FIG. 3A is a schematic perspective view of the drum 21-1, and FIG. 3B isan exploded perspective view of the drum 21-1. The drum 21-1 has acylindrically formed display panel 31, a cylindrically formed lightguide plate 32 provided along the outer circumference of the displaypanel 31, a light source unit 33 provided along a portion of the sidesurface of the light guide plate 32, and a casing 34 that supports thedisplay panel 31, the light guide plate 32 and the light source unit 33.

The display panel 31 and the light guide plate 32 are attached to thecasing 34 such that shafts thereof that are substantially horizontal andsubstantially parallel to the front surface of the main body casing 1are coaxial with each other, in a state where the drum unit 2 isattached to the main body casing 1. The display panel 31 is attached toa rotation shaft (not shown) via a support member 31 a provided insidethereof. The rotation shaft of the display panel 31 is connected viagears to a rotation shaft of a stepping motor (not shown) for use indriving the display panel 31. As a result of the stepping motor rotatingaccording to a control signal from the control circuit, the displaypanel 31 rotates in the vertical direction with the rotation shaft asthe rotation center.

The surface of the display panel 31 is divided in the rotation directioninto a plurality of regions each having substantially the same width,and various patterns are depicted in the different regions, with aportion of these regions being visible to the gamer through the lightguide plate 32 and the opening 11.

The light guide plate 32 is also attached to a rotation shaft (notshown) provided coaxially with the rotation shaft of the display panel31 via a support member 32 a provided on the inside thereof, and can beindependently rotated relative to the display panel 31. The rotationshaft of the light guide plate 32 is connected via gears to a rotationshaft of a stepping motor (not shown) for use in driving the light guideplate 32. The light guide plate 32 rotates in the vertical direction, asa result of the stepping motor for use in driving the light guide plate32 rotating according to a control signal from the control circuit.

Note that, according to a variation, the light guide plate 32 may befixedly attached coaxially to the display panel 31, so as to not rotate.

The light source unit 33 has a plurality of light emitting elements 35that emit visible light such as light emitting diodes, for example. Thelight emitting elements 35 are arranged in a row along one sidewall ofthe light guide plate 32, at a position overlapping with the opening 11of the main body casing 1. The light emitting elements 35 are arrangedsuch that the light emitting surface of each light emitting element 35opposes the light guide plate 32. For example, the light emittingelements 35 are arranged such that the direction in which the lightemission intensity thereof is strongest is orthogonal to the sidewall ofthe light guide plate 32 that serves as the incident surface thereof.The light source unit 33 turns each light emitting element 35 on or offaccording to a control signal from the control circuit. At that time,the light source unit 33 may turn on all of the light emitting elements35 at the same time, or may turn on only some of the light emittingelements 35.

Hereinafter, the light guide plate 32 will be described in greaterdetail.

The light guide plate 32 is formed by cylindrically molding a resin thatis transparent to visible light, such as polymethyl methacrylate (PMMA),polycarbonate or cycloolefin polymer, for example, so that the patternsof the display panel 31 arranged on the inner circumferential side ofthe light guide plate 32 are visible to the gamer through the lightguide plate 32. Also, the light guide plate 32 displays a predeterminedpattern using the light from the light source unit 33.

FIG. 4A is an enlarged partial view of the light guide plate 32. Also,FIG. 4B is a cross-sectional side view of the light guide plate 32 asseen from the direction of arrows AA′ in FIG. 4A. It should be notedthat, in FIG. 4B, dimensions such as the thickness of the light guideplate 32 and the size of each prism are exaggerated for convenience ofdescription. As shown in FIGS. 3A, 4A and 4B, one of the sidewalls ofthe light guide plate 32 is an incident surface 32 b opposing the lightemitting elements 35 of the light source unit 33. Light from the lightemitting elements 35 enters the light guide plate 32 through theincident surface 32 b.

In a diffusing surface 32 c, which is the surface on the innercircumferential side of the light guide plate 32, that is, the surfaceon the side opposing the display panel 31, a plurality of prisms 321 areformed in a grid at a predetermined pitch along a pattern 32 d. Notethat the plurality of prisms 321 may be arranged so as to be staggeredat a predetermined pitch. The plurality of prisms 321 reflect the lightfrom the light emitting elements 35 that enters the light guide plate 32from the incident surface 32 b and cause the reflected light to exitfrom an exit surface 32 e, which is the surface on the outercircumferential side of the light guide plate 32, such that the pattern32 d appears to emit light. Note that the pattern 32 d can be anypattern that allows a plurality of prisms 321 to be arranged within thepattern 32 d. Also, the pattern 32 d may have a different sub-patternfor every different position in the rotation direction of the lightguide plate 32. As a result of the light guide plate 32 rotating, thegamer is thereby able to see different patterns.

Each of the plurality of prisms 321 is, for example, formed in thediffusing surface 32 c as a substantially triangular groove having apredetermined length. Each of the plurality of prisms 321 has areflecting surface 321 a oriented toward the incident surface 32 b sideso as to form a predetermined angle with the diffusing surface 32 c andoppose the light emitting elements 35. In the present embodiment,because the light emitting elements 35 are arrayed along one sidewall ofthe light guide plate 32 which rotates in the vertical direction, lightfrom the light emitting elements 35 propagates inside the light guideplate 32 so as to spread up and down about the horizontal direction. Forthis reason, the reflecting surface 321 a of the prisms 321 is formed soas to be oriented substantially in the horizontal direction. Note thatthe predetermined angle is an angle at which light from the lightemitting elements 35 that enters the light guide plate 32 is totallyreflected toward the exit surface 32 e, and is set to be 40 to 50degrees relative to the diffusing surface, for example. Also, thepredetermined length is set from about 100 μm to several millimeters,for example.

As discussed above, light from the light emitting elements 35 entersinside the light guide plate 32 from the incident surface 32 b. Lightpropagated inside the light guide plate 32 then exits from the exitsurface 32 e after being totally reflected by the plurality of prisms321 formed in the diffusing surface 32 c. Because the plurality ofprisms 321 are arrayed along the pattern 32 d, the gamer is able to seethe pattern 32 d which appears to emit light, through the opening 11,together with the pattern provided on the surface of the display panel31, while the light emitting elements 35 are on. On the other hand,while the light emitting elements 35 are off, the gamer is able to seeonly the pattern provided on the surface of the display panel 31 throughthe opening 11. In this way, the pattern that is visible to the gamercan be switched by on/off control of the light emitting elements 35.Furthermore, because the display panel 31 and the light guide plate 32are rotatable independently from each other, changing the combination ofthe portion of the display panel 31 that faces the opening 11 and theportion of the light guide plate 32 that faces the opening 11 enablesthe combinations of patterns on the drum 21-1 that are visible to thegamer to be variously changed.

Furthermore, the path of light from the light emitting elements 35 tothe gamer becomes longer as the distance from the incident surface 32 bincreases. Also, because the light from the light emitting elements 35is specularly reflected by the prisms 321, the light appears to beshining at a greater depth, the further the position is from theincident surface 32 b. Thus, the pattern 32 d is displayedthree-dimensionally.

Also, in the present embodiment, the light guide plate 32 is curved inthe vertical direction. Thus, light from light emitting elements 35 thatare located higher than the position of the foot of a perpendicular fromthe position of the gamer's eyes to the surface of the light guide plate32 is reflected toward the gamer by prisms that are located lower downas the distance from the incident surface increases. Note that lightfrom these light emitting elements 35 that is incident perpendicular tothe incident surface 32 b is reflected above the position of the gamer'seyes.

Conversely, light from light emitting elements 35 that are located lowerthan the position of the foot of this perpendicular is reflected towardthe gamer by prisms that are located higher up as the distance from theincident surface increases. Note that light from these light emittingelements 35 that is incident perpendicular to the incident surface 32 bis reflected below the position of the gamer's eyes. Accordingly, lightfrom the individual light emitting elements appears to the gamer to belinear within the pattern 32 d, and also the interval between lightbeams appears to narrow, the further the distance is from the incidentsurface 32 b.

In view of this, according to a variation, the prisms may be formed suchthat, in the case where the light guide plate 32 stops at apredetermined rotation position, the reflecting surface of prisms thatare located above the position of the foot of the perpendicular from theassumed position of the gamer's eyes to the surface of the light guideplate 32 is oriented more toward the foot, the further the distance isfrom the position of the foot, and the reflecting surface of prisms thatare located below the position of the foot of this perpendicular isoriented more toward the foot, the further the distance is from theposition of the foot. It is thereby possible to show patterns to thegamer such that light from the individual light emitting elements formsparallel light beams.

Furthermore, the arrangement density, which is a ratio of the area ofthe region in which the prisms 321 are formed to the area of the regionin which the pattern 32 d is formed is preferably less than or equal toan upper limit of the arrangement density at which the gamer feels asthough he or she is viewing the pattern displayed on the display panel31, which is on the inner circumferential side of the light guide plate32, through a transparent member or through empty space, when the lightemitting elements 35 are off. In view of this, the prisms 321 arepreferably formed such that the arrangement density is 30.0% or less,for example.

Alternatively, a haze value representing the proportion of diffusedlight to all transmitted light is preferably less than or equal to anupper limit of the haze value at which the gamer feels as though he orshe is viewing the pattern displayed on the display panel 31, which ison the inner circumferential side of the light guide plate 32, through atransparent member or through empty space, when the light emittingelements 35 are off. The prisms 321 are preferably formed such that thehaze value is 28% or less, for example.

FIG. 5A is a schematic perspective view of the decoration device 22-1according to one embodiment of the present invention, and FIG. 5B is anexploded perspective view of the decoration device 22-1. As shown inFIGS. 5A and 5B, the decoration device 22-1 has a display panel 41, alight guide plate 42, and two light source units 43-1 and 43-2.

The display panel 41 is arranged such that the longitudinal directionthereof is in the circumferential direction of the drum 21-1. Thus, thedisplay panel 41 has a cylindrical surface shape whose longitudinaldirection is curved along the outer circumference of the drum 21-1. Apattern that depends on the presentation is depicted on the surface ofthe display panel 41, and the pattern is visible to the gamer throughthe light guide plate 42 and the opening 11.

The light guide plate 42 is provided on the surface of the display panel41, that is, the surface on the gamer side of the display panel 41, anddisplays a pattern formed by the light from the light emitting elementsof the light source units 43-1 and 43-2 to the user, so as to besuperimposed on the pattern on the display panel 41. Thus, the lightguide plate 42 has a cylindrical surface shape whose longitudinaldirection is curved along the surface of the display panel 41, and isformed by molding a resin that is transparent to visible light, such aspolymethyl methacrylate (PMMA), polycarbonate and cycloolefin polymer,for example.

The light source unit 43-1 has a plurality of light emitting elements44-1 that emit visible light such as light emitting diodes, for example.The light emitting elements 44-1 are arranged in a row along the upperend of the light guide plate 42. The light emitting elements 44-1 arearranged such that the light emitting surface of each light emittingelement 44-1 opposes the upper end of the light guide plate 42. Forexample, the light emitting elements 44-1 are arranged such that thedirection in which the light emission intensity thereof is strongest isorthogonal to the upper end of the light guide plate 42. The lightsource unit 43-1 turns each light emitting element 44-1 on or offaccording to a control signal from the control circuit. At this time,the light source unit 43-1 may turn on all of the light emittingelements 44-1 at the same time, or may turn on only some of the lightemitting elements 44-1.

Similarly, the light source unit 43-2 has a plurality of light emittingelements 44-2 that emit visible light such as light emitting diodes, forexample. The light emitting elements 44-2 are arranged in a row alongthe lower end of the light guide plate 42. The light emitting element44-2 are arranged such that the light emitting surface of each lightemitting element 44-2 opposes the lower end of the light guide plate 42.For example, the light emitting elements 44-2 are arranged such that thedirection in which the light emission intensity is strongest isorthogonal to the lower end of the light guide plate 42. The lightsource unit 43-2 turns each light emitting element 44-2 on or offaccording to a control signal from the control circuit. At this time,the light source unit 43-2 may turn on all of the light emittingelements 44-2 at the same time, or may turn on only some of the lightemitting elements 44-2. Note that a light source unit may be provided atonly the upper end or the lower end of the light guide plate 42.

FIG. 6A is an enlarged partial view of the light guide plate 42. Also,FIG. 6B is a schematic partial cross-sectional view of the light guideplate 42 in vertical cross-section. It should be noted that, in FIG. 6B,only some of the prisms are displayed, and that dimensions such as thesize of the prisms and the thickness of the light guide plate areexaggerated for convenience of description. As shown in FIGS. 6A and 6B,the upper end surface and the lower end surface of the light guide plate42, that is, both end surfaces of the light guide plate in the directionin which the light guide plate has curvature, are each an incidentsurface 42 b. Light from the light emitting elements enters the lightguide plate 42 through the incident surfaces 42 b.

In a diffusing surface 42 c, which is a concave cylindrical surface onthe back surface side of the light guide plate 42, that is, on the sideopposing the display panel 41, a plurality of prisms 421 are formed in agrid at a predetermined pitch along a pattern 42 d. Note that theplurality of prisms 421 may be arranged so as to be staggered at apredetermined pitch. The plurality of prisms 421 reflect light from thelight emitting elements 44-1 that enters the light guide plate 42 fromthe incident surface 42 b at the upper end or light from the lightemitting elements 44-2 that enters the light guide plate 42 from theincident surface 42 b at the lower end, and cause the reflected light toexit from an exit surface 42 e, which is a convex cylindrical surfaceopposing the diffusing surface 42 c, such that the pattern 42 d isvisible to the gamer. Note that the pattern 42 d can be any pattern thatallows a plurality of prisms 421 to be arranged within the pattern 42 d.

Each of the plurality of prisms 421 is, for example, formed in thediffusing surface 42 c as a substantially triangular groove having apredetermined length. Each of the plurality of prisms 421 has areflecting surface 421 a oriented toward the incident surface 42 b sideso as to form a predetermined angle with the diffusing surface 42 c andoppose the light emitting elements 44-1 or the light emitting elements44-2. In the present embodiment, because the light emitting elements44-1 and the light emitting elements 44-2 are arrayed along the upperend or the lower end of the light guide plate 42, light from the lightemitting elements propagates inside the light guide plate 42 so as tospread right and left about the vertical direction. Thus, the reflectingsurface 421 a of the prisms 421 is formed so as to be orientedsubstantially in the vertical direction. Note that the predeterminedlength is set from about 100 μm to several millimeters, for example.

Light from the light emitting elements 44-1 and 44-2 enters inside thelight guide plate 42 from the incident surface 42 b. Light propagatedinside the light guide plate 42 then exits from the exit surface 42 e,after being totally reflected by the plurality of prisms 421 formed inthe diffusing surface 42 c. Because the plurality of prisms 421 arearrayed along the pattern 42 d, the gamer is able to see the pattern 42d which appears to emit light, through the opening 11, together with thepattern provided on the surface of the display panel 41, while the lightemitting elements 44-1 and 44-2 are on. On the other hand, while thelight emitting elements 44-1 and 44-2 are off, the gamer is able to seeonly the pattern provided on the surface of the display panel 41 throughthe opening 11. In this way, the pattern that is visible to the gamercan be switched by on/off control of the light emitting elements 44-1and 44-2.

Note that, according to a variation, a plurality of prisms 421 may beprovided over the entire diffusing surface 42 c. In this case, thedecoration device 22-1 is able to show patterns to the gamer as thoughthe entire light guide plate 42 is lit up, while the light emittingelements 44-1 and 44-2 are on.

As discussed above, the light guide plate 42 curves such that thediffusing surface 42 c side is concave in the longitudinal direction,that is, in the vertical direction. Thus, when the angle of thereflecting surface 421 a of each prism relative to the diffusing surface42 c is the same, the reflecting surface 421 a is oriented moreupwardly, the closer the prism is to the upper end of the light guideplate 42, and is conversely oriented more downwardly, the closer theprism is to the lower end of the light guide plate 42, resulting in thelight that exits from the exit surface 42 e spreading vertically. Inview of this, in the present embodiment, the prisms 421 are formed suchthat the angle of the reflecting surface 421 a relative to the diffusingsurface 42 c increases, the closer the prism is to the midpoint of thelight guide plate 42 in the vertical direction, that is, the further theprism is from the incident surface 42 b. For example, if the angleformed by a line connecting to the center of the arc along the diffusingsurface 42 c from an arbitrary position P on the diffusing surface 42 cand a line connecting between the center of the arc and a midpoint ofthe diffusing surface 42 c in the vertical direction is given as θ, theprisms 421 are preferably formed such that the angle formed by thereflecting surface 421 a of the prism 421 and the diffusing surface 42 cat the position P will be (45−θ/2±α)° (where α is 0 to 5, for example).Thereby, irrespective of the position of the prism, the orientation ofthe center of distribution of light that is reflected by that prism andexits from the exit surface 42 e of the light guide plate 42 will besubstantially parallel to the line connecting the midpoint of thediffusing surface 42 c in the vertical direction and the center of thearc along the diffusing surface 42 c. Thus, the luminance distributionof light that exits the light guide plate 42, when the decoration device22-1 is seen from the direction along an extension of that line, will besubstantially uniform.

Furthermore, the prisms are preferably formed such that the size of thereflecting surface 421 a increases, the further the prism is from themidpoint of the light guide plate 42 in the vertical direction. Becausethe difference in apparent size of the reflecting surfaces of theprisms, when the decoration device 22-1 is seen from the direction alongan extension of the line connecting the midpoint of the diffusingsurface 42 c in the vertical direction and the center of the arc alongthe diffusing surface 42 c, can be reduced, the luminance distributionof light that exits from the light guide plate 42, when the decorationdevice 22-1 is seen from that direction, can be equalized.

Note that, similarly for the light guide plate 42, the arrangementdensity, which is a ratio of the area of the region in which the prism421 is formed to the area of the region in which the pattern 42 d isformed, is preferably less than or equal to an upper limit of thearrangement density at which the gamer feels as though he or she isviewing the pattern displayed on the display panel 41 through atransparent member or through empty space, when the light emittingelements 44-1 and 44-2 are off. In view of this, the prisms 421 arepreferably formed such that the arrangement density is 30.0% or less,for example.

Alternatively, similarly for the light guide plate 42, a haze valuerepresenting the proportion of diffused light to all transmitted lightis preferably less than or equal to an upper limit of the haze value atwhich the gamer feels as though he or she is viewing the patterndisplayed on the display panel 41 through a transparent member orthrough empty space, when the light emitting elements 44-1 and 44-2 areoff. The prisms 421 are preferably formed such that the haze value is28% or less, for example.

In the present embodiment, because the path of light from the lightemitting elements 44-1 or 44-2 to the gamer becomes longer as thedistance to the midpoint of the light guide plate 42 decreases in thevertical direction, the light appears to be shining at a greater depth,the closer the position is to the midpoint of the light guide plate 42in the vertical direction. Thus, the pattern 42 d is displayedthree-dimensionally. Also, by arranging the light emitting elements suchthat the horizontal position of the light emitting elements 44-1 and thehorizontal position of the light emitting elements 44-2 coincide, thepattern 42 d can be shown as though lit up linearly from within alongstraight lines connecting the light emitting elements 44-1 and the lightemitting elements 44-2.

As described above, this light guide plate and the decoration deviceusing the light guide plate are able to switch the pattern that isdisplayed simply by switching the light emitting elements between on andoff, thus enabling a reduction in the number of the light emittingelements that are required to switch the pattern that is displayed.Furthermore, this light guide plate and the decoration device using thelight guide plate can be attached to a portion that curves in an arc,and are able to cause light that propagates inside the light guide plateto exit in a specific direction.

Note that the present invention is not limited to the foregoingembodiments. For example, this decoration device may be utilized indecorating structures having a cylindrical surface shape in other gamemachines or various devices that use decoration using illuminated light.

A person skilled in the art will thus be able to make variousmodifications within the scope of the invention, in accordance withmodes to be carried out.

1. A decoration device comprising: a display panel formed to have acylindrical surface shape with curvature in a first direction, and onwhich a first pattern is provided; a light source configured to emitvisible light; and a light guide plate arranged such that a diffusingsurface that diffuses visible light incident thereon after being emittedfrom the light source opposes the display panel, the diffusing surfacebeing formed to have a concave cylindrical surface shape with curvaturein the first direction, an exit surface opposing the diffusing surfacebeing formed to have a convex cylindrical surface shape with curvaturein the first direction, and the light guide plate being constituted suchthat the first pattern is visible from the exit surface side, whereinthe light guide plate includes: an incident surface formed on an endsurface that opposes the light source in the first direction of thelight guide plate; and a plurality of prisms that are formed in thediffusing surface and reflect visible light that enters the light guideplate from the incident surface toward the exit surface, and each of theplurality of prisms has a reflecting surface oriented toward theincident surface side, and an angle between the reflecting surface andthe diffusing surface increases as a distance of the prism from theincident surface increases.
 2. The decoration device according to claim1, wherein the plurality of prisms are arranged along a second pattern.3. The decoration device according to claim 1, wherein each of theplurality of prisms is formed such that an area of the reflectingsurface increases, the closer the prism is to the incident surface amongthe plurality of prisms.
 4. A game machine comprising the decorationdevice according to claim 1.